I’m going with “strapped to the side of a rocket and launched into orbit.” Because hell, I’m going to pass out and die from lack of oxygen, but what a last few minutes of life!
Those only appear painless because the body is so badly incapacitated the mind can no longer translate its will into action via the brain. Once death proper takes hold and the physical structure is beyond repair, the mind/soul/whateveryouwannacallit begins its final disengagement. Like having one’s hide peeled off, the experience is said to be excruciating. The trauma of this process is worsened if death is resisted or denied because the mind will struggle to retain its hold on the decaying and increasingly unresponsive brain. It’s a difficult process, but it builds character.